I've been thinking about getting one of these recently because when I had heat problems at the last track day, high revs alone really seemed to aggravate it, suggesting cavitation was a factor which is a known problem with these engines. I've been looking at the T3 +18% pulley in particular. I've heard that sometimes underdrive WP pulleys cause cooling problems at idle, which I definitely can't have. Anyone have any experience with a 4AGE in particular?
What condition is the radiator in? What radiator fluid and what ratio are you using?
I used to beat on my 20v AE92 pretty darn hard. The only times I ever had it overheat was when a heater hose blew out and I lost the fluid and when the radiator turned to dust one day on the way to work.
If your radiator is in good condition, you should be using only Toyota Red coolant and if you're having issues, use a ratio of 1:2, that is 1 part Toyota Red and 2 parts distilled water. Not 50:50, 1/3rd Red. And add a bottle of Water Wetter.
I agree with Dr. Hess.^^^^^^
When I had cooling problems with he FX16 it was because of the deteriorating radiator. Only had issues after back to back autocross runs. A new radiator fixed it! I'm running a 50/50 Toyota Red coolant/water mix with no issues.
It's a 1-row radiator (stock JDM, US models got a 2-row), decent shape (just a few chewed fins on the back) running about 1/4~1/3rd Prestone Orange with Water Wetter.
This was also the first time I'd had any engine in this chassis go significantly above normal operating temperature without a hose blowing out. I'm sure the fact that I had some too-lean areas on the fuel map was part of it, but after the engine cooled down I went back out just keeping it under 6500rpm without any other changes, and while the temp did slowly creep above normal over the course of a few laps it was nothing like the first time out, where temps skyrocketed by the end of the 2nd lap.
My radiator is an OEM replacement single row.
No overheating while bouncing off the 7,500 rpm redline.
Hmm maybe mine is giving up the ghost. A local radiator shop told me they could re-core my current radiator with a 2-row core for $350. Maybe I should go that route.
Do you not have an O'Reilley's on your little island? Hell of a lot cheaper than three and a half bills. Oh well. Yeah, start with a new radiator if that one is original or a couple decades old,and a 2 core would probably fix your problems. I used to hit the 8K rev limiter EVERY BERKELEYING DAY in that car. I have not heard of cavitition being a problem on any 4AG motor. Far as I know, the 16v Formula Atlantic motors used the same water pump. I never heard of a different one. Different cranks to handle 10K RPM all day long, yeah, but never heard of a different water pump or drive. I think your overheating at extended high RPM is more of a high HP/high heat generating and weak cooling system, rather than cavitation, but that's my GUESS.
Dr. Hess wrote: Do you not have an O'Reilley's on your little island? Hell of a lot cheaper than three and a half bills.
There are parts stores selling replacement radiators, but they cost about twice as much as they do in the US due to import duties. And they're all 1-row and plastic-tanked 
Check your thermostat. It could stop functioning 100%. And only be like 75% travel. Also, check shaft play on the water pump and be certain the pump isn't missing a fin. It happens. Happened to me on a z car. I web too the pump off, check shaft play and looked at the fins. I saw one was missing and said "hey that's good enough!" Man was I wrong.
All those parts are new on my car (and are Toyota-brand parts) - they only have a few hours of run-time on them.
The radiator probably is 25 years old now, looks like a factory unit.
Oh, 25yr old radiator? C'mon man, change that thing.
Thread resurrection: I'm still running the same radiator but I've sorted out the tuning problems that were producing extra waste heat. However the extra revs still make the engine uncomfortably hot fairly quickly on track. I have the ECU set to activate a 5krpm limiter at 215F and shut down the engine at 230F. If i avoid spending time above 6.5krpm, the car can run flat out all day long in the 200F~210F ballpark. If I run it higher, it goes from 180F to 215F within 3~4 laps of the 1:30ish circuit, a lap of cruising gets me another 2~3 laps of screaming high revs, or infinite laps of driving under 6.5krpm.
I'm already running a good coolant mixture and a 16psi radiator cap. Possible solutions are:
- Changing the radiator to something better: $350+ (options range from "2-row recore from local shop" at $350 to "custom aluminum rad." at "you have to ask..." Remember that a radiator is too big to smuggle in, so whatever you can find online will cost at least 2x as much once it's in my hands.)
- Auxiliary cooler on the heater ports: $50~100 (downsides: possible overcooling on street, increased weight)
- Underdrive water pump pulley: $100 (downside: possible toastiness on street)
The only other cheap improvements I can make are to radiator airflow (ducting, swapping one of the fans from a pusher to a puller, maybe moving oil and PS coolers to side vents). If pump cavitation is the problem, the underdrive pulley could be the best fix, and adding cooling capacity with a better or auxiliary radiator would actually be treating the symptom. But I don't know whether it will cool well at lower RPMs.
I don't see how an underdrive pulley is going to help you out here, unless you think you have cavitation at those RPM's. I bet it's more a matter of more heat generated than can be dumped.
What are you running for coolant? The best you can get is 100% distilled water with a bottle of Redline Water Wetter. Best you can get with still having the advantages of "anti-freeze," which isn't really needed for the non-freezing aspects where you live, but more for the increased boiling temp and corrosion prevention, is 1/3rd antifreeze, 2/3rds distilled water and a bottle of Water Wetter.
Right now I'm running 1/3rd cheapo green stuff and tap water, unfortunately I lost my 1/3rd Prestone orange + water wetter and distilled water in a hose blowout on the street and had to do a roadside refill with what I have now (luckily the guy I was headed to happened to have an AE92 lower radiator hose at home). Peak temps on track are about the same between the two according to ECU data logs.
GameboyRMH said:Thread resurrection: I'm still running the same radiator
You're running a 30-year old rad and complaining about temps? Comon' son, those old copper tubes have probably caught tons of scale now and no amount of flushing would ever remove it.
One thing you're not mentioning is the car you're running, which makes a big deal. I've got an AW11 MR2 with the 4A, and the stock rad is fine (for what it is) but the fans and the shroud are massively heavy and the aftermarket has long since improved upon them.
The other issues- you're using basic coolants, and while I typically agree that antifreeze is just that there are some differences. Go for an Asian red coolant which they recommend. IF you have an AW11 as well, make sure you're using an OEM Thermostat with the tiny drip hole in the metal collar- rockauto specials will work "well enough" but that hole REALLY helps when bleeding.
The car is the AE92 in my avatar, you can see details in my garage entry. I am running an OEM thermostat.
If possible, plumb a pressure gauge into the water jacket. 0-100psi oil pressure gauge should be fine.
Look for a change at high RPM.
it should ramp right on up to 30-60psi water pressure, but if you have a pump cavitation issue, the pressure will flutter and drop like a rock. I have also seen thermostats get pushed shut by high water flow, which makes the pressure in the block spike. Either way, you will be watching for a change.
I do think you are on the right track, as everything you said indicates it is an RPM related issue and NOT a generally insufficient cooling issue. It may even not be as interesting a problem as needing to slow the pump down: The thermostat may be getting weak, the water pump may have corroded fins/been manufactured wrong so there is a large end gap from the impellers, or the lower radiator hose might simply be sucking shut because the spring that is supposed to be in it has corroded away.
...you DO have a spring in the lower hose don't you?
I would not worry about idle temps. I have a 33% underdrive pulley on one of my RX-7s (the water pumps stall at about 6000rpm, causing the exact problem you are having...) and low RPM cooling is not an issue.
The pressure gauge in the water jacket is about as much work and expense as chucking some of the potential solutions at the car to see what works, unfortunately...I don't know if there's a spring in the lower hose. I dissected the old lower hose that blew up a while ago and there was no spring in it. I guess I could just look in the engine bay to see if it gets sucked shut at high revs.
The thermostat and water pump are only a few years old, the water pump in there now isn't a Toyota genuine unit but a good quality Japanese unit with a cast impeller shaped kind of like a turbo compressor wheel.
With everything cold, you can just grab the lower hose and squeeze it to check for a spring. Loosen the radiator cap first and expect some overflow.
In reply to GameboyRMH :
New doesn't mean right. Learned to check impeller height of new vs. old.
Previous one was the same model, so at least I'm keeping it consistent 
I'll do the tests on the lower hose this evening.
OK so there's no spring in the lower hose, I can easily pinch it flat with my fingers anywhere. Unfortunately by the time it stopped raining last night, it was too late for any limiter-banging tests, I'll try again this evening.
Update: I think I've fixed or sufficiently mitigated the problem without changing any parts. It seems most of it was due to a lean spot in the fuel map around 4krpm at low to medium load. When I shifted at high revs, the engine passed through this area of the map when going back onto the gas which caused a temperature spike, over the course of a few laps the cumulative effect of these spikes would cause the engine to become uncomfortably hot. If I shifted at lower RPMs, I'd avoid this part of the map.
Yesterday was the first track day I made it to since I richened up that area, and even though it was an exceptionally hot day I was able to do two full 15-minute sessions at high revs without the engine getting too hot. In the first session it peaked well under 210F, in the second it barely stayed under my "limp mode" limit of 215F but that was a huge improvement over getting just a few laps in before exceeding it.
I think there's a bit more room to reduce heat through engine tuning and lots more room for improving airflow through the radiator.
Have you put a timing light on it to verify what your timing matches what you tuning said it is supposed to be set at? Almost sounds like you have timing retarding as the rpms go up. Did you by chance get a base map from a motor with boost?
I've been using maps very close to the stock maps for the 4AGE bigport and smallport models. I think on Sunday I actually had a bit too much advance at high RPMs using a bigport-like map that gives it a couple extra degrees at full load and high revs, I think I'm going to take that out and make it more like the smallport map. I have the engine set to retard a couple of degrees at high IATs, so it tends to go more advanced as the car spends more time at higher speeds. I noticed the high-RPM power getting weaker later in the session so that suggests too much advance.
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